In percutaneous transhuninal angioplasty (“PTA”) and percutaneous transluminal coronary angioplasty (“PTCA”) procedures, a dilation balloon is typically advanced intravascularly to a stenosed region and inflated to open the blockage and/or place a stent.
Restenosis, where treated vessels such as coronary arteries tend to become re-occluded (such as following stent implantation), has been addressed by improvements in stent design, delivery systems, and techniques along with the development of drug eluting stents. Typically, a balloon expandable stent is delivered to the coronary arteries using a long, flexible vascular catheter with a balloon on the distal end over which the stent is mounted. The delivery catheter is introduced into the vascular system percutaneously through a femoral or radial artery. Once the catheter is positioned at the target treatment site, the delivery catheter balloon is expanded which correspondingly expands and permanently deforms the stent to a desired diameter. The balloon is then deflated and removed from the vessel, leaving the stent implanted in the vessel at the lesion site.
It may be advantageous to deliver therapeutic agents to a vascular treatment site in combination with balloon angioplasty or stenting. Various methods have also been suggested for delivering drug agents to a dilation site. One technique for delivering such agents is through the use of drug eluting stents which have a coating containing the agent over their exterior. As an alternative, it has been suggested that thin walled flexible balloons having a plurality of small holes could be used to contact the vessel wall and deliver agents upon expansion. Other examples include balloons which are simply coated with a drug and expanded into contact against the treatment site.
However, the length of the treatment region within the vessel may be variable depending upon the patient condition. Because lesion sizes may vary between patients, a balloon catheter having a fixed treatment length for drug delivery may require multiple treatments for a relatively long lesion resulting in increased treatment times and complications. Alternatively, for relatively short lesions, treatment with an excessively long balloon may result in over treatment of the tissue region and unnecessary application or infusion of drugs into the patient system. Although fluoroscopy and angiography may be used to evaluate the lesion prior to catheter insertion, sometimes lesion length cannot be assessed accurately.
It would therefore be desirable to provide drug delivery catheters that could be customized in length at the site of treatment in order to precisely tailor the device to the size of the region to be treated. In addition, it would be desirable if such drug delivery catheters could be used not only for drug delivery, but also for balloon angioplasty and stent delivery as well.
Further, it would be desirable to deliver therapeutic agents and perform balloon angioplasty and/or deliver one or more stents in the same intervention without the need to exchange catheters.